1. Field of the Invention
The present invention relates to a liquid-crystal display apparatus and a method for manufacturing a liquid-crystal display, and more particularly to temperature detection technology used in a liquid-crystal display apparatus that employs active matrix.
2. Background of the Invention
In the past, technology for this type of temperature detection circuit is known from the disclosure of the Japanese Unexamined Patent Publication (KOKAI) No. 60-107023. Specifically, as shown in FIG. 8, the above-mentioned technology is that a temperature is detected by means of a thermally sensitive element attached by adhesion or the like to an outside surface of a TFT substrate or color filter substrate, the consumed power being minimized, by a subsequent temperature control circuit, based on the detected temperature. However, There are many problems as follows.
The first problem is that it is not possible to detect the temperature of a liquid-crystal layer with accuracy. The reason for this is that, in prior art, the construction was such that the thermally sensitive element was attached by adhering to an outside surface of a substrate in a protruding condition, so that supporting members to fix the liquid crystal display panel and thermally sensitive element thereon and TFT substrate and color filter substrate serve as heat radiators.
That is, in the above-noted prior art, because the thermally sensitive element detects a temperature of the liquid-crystal layer in an environment in which the thermally sensitive element was exposed to the outside air on an outside surface of a TFT substrate or color filter substrate, the obtained result was different from the temperature within the liquid-crystal layer, a temperature of thermal equilibrium between the outside air and the TFT or color filter substrate to which the thermally sensitive element is attached, is detected. Because the above-mentioned temperature is different from the temperature of the liquid crystal layer that is sealed within these two substrates, it is not possible to accurately transmit the temperature of the liquid-crystal layer itself to a temperature compensation circuit that optimizes a drive signal that is applied to the liquid-crystal layer in response to temperature changes with respect to the surrounding environment.
The second problem accompanying the prior art was that, because of an increase in the number of components and the number of assembly steps, there was an increase in cost. The reason for this is that the parts and materials such as the thermally sensitive element and adhesive for adhering, the wiring for transmitting the temperature control signal to the external temperature control circuit and the time required for curing of the adhesive, and the number of structural parts and assembly steps for providing an escape so that the thermally sensitive element does not come into contact with the housing that protects and supports the liquid-crystal panel, increase, thereby causing an increase in the cost.
Accordingly, it is an object of the present invention to accurately detect the temperature of a liquid-crystal layer in a liquid-crystal display panel, and achieve proper temperature compensation in response to temperature changes.
It is another object of the present invention to reduce the number of components in a liquid-crystal display panel and assembly steps, and achieve a reduction in size and weight of a liquid-crystal display panel.
Yet another object of the present invention is to achieve a simplification of the circuit and configuration of a liquid-crystal display panel.
Yet another object of the present invention is to reduce the number of components and assembly steps for a liquid-crystal display panel, and to achieve an improvement in productivity thereof.
Yet another object of the present invention is to accurately detect the temperature of a liquid-crystal display panel, and to perform appropriate temperature compensation in response to a temperature change, thereby achieving an improvement in display performance.
In order to achieve the above-noted object, the present invention has the following technical constitution.
A first aspect of the present invention is a liquid-crystal display apparatus comprising a liquid-crystal display panel having a first substrate on which a plurality of scannig lines and a plurality of signal lines are disposed perpendicularly, and on which a plurality of pixel electrodes are provided so as to be connected to intersections between the scannig lines and the signal lines via a switching element, respectively, a second substrate disposed in opposition to the first substrate, and a liquid-crystal layer sandwiched between the first substrate and the second substrate; wherein a temperature detection element for detecting a temperature within the liquid-crystal layer is provided on the first substrate, the temperature detection element is provided in a light-blocking region formed in an outer periphery of a display region of the liquid-crystal display panel.
In the second aspect of the present invention, the switching element is a thin-film transistor, and the temperature detection element is a thin-film transistor.
In the third aspect of the present invention, the switching element is a thin-film transistor, and the temperature detection element is a thin-film diode or a thin-film constant-voltage diode.
In the fourth aspect of the present invention, a semiconductor layer of the switching element and the temperature detection element is made of amorphous silicon.
In the fifth aspect of the present invention, a liquid crystal driving circuit connected to the signal lines, is provided, and an output terminal of the temperature detection element is coupled to a wiring on a tape carrier package on which the liquid crystal driving circuit is provided.
A sixth aspect of the present invention is a method of manufacturing a liquid-crystal display apparatus comprising a first substrate having a switching element to control a pixel electrode, a second substrate disposed in opposition to the first substrate, and a liquid-crystal layer sandwiched between the first substrate and the second substrate, wherein in a step of forming the switching element on the first substrate, a temperature detection element that detects a temperature of the liquid-crystal layer is formed on the same surface of the first substrate as the switching element is provided.
In a seventh aspect of the present invention, the temperature detection element formed on the first substrate is a thin-film transistor.
In a eighth aspect of the present invention, the temperature detection element formed on the first substrate is a thin-film diode.
More specifically, in the present invention, a temperature detection element formed by a thin-film transistor or thin-film diode on a light-blocking black mask part of a liquid-crystal display panel is formed simultaneously in the process step that forms the thin-film transistor or thin-film diode for driving the liquid crystal pixels, and an unused output terminal of the TCP common electrode voltage supplying terminals on the tape carrier package is used as a lead wire for the temperature detection element. This temperature detection element performs detection of the temperature by utilizing the characteristic of an increase in the drain current in proportion to the temperature of the liquid-crystal layer that changes with a change in the environmental temperature. Therefore, it is possible using a simple configuration to accurately detect the temperature of the liquid-crystal layer that changes with a change in the environmental temperature.